Shunting device



F. l. LOVRET SHUNTING DEVICE Filed Feb. 1. 1960 March 20, 1962 JNVENTOR. FPEDE-Q/CK f. Lox/e57" 3,026,392 SHUNTING DEVICE Frederick I. Lovret, Norman, Okla., assignor to L & M Space Research and Electronics Corporation, Norman, Okla, a corporation of Oklahoma Filed Feb. 1, 1960, Ser. No. 5,990 6 Claims. (Cl. 200-118) This invention relates generally to improvements in devices for automatically shunting the current around an open or broken electrical circuit, and is particularly useful in shunting the current around a broken neon tube.

As it is well known in the Neon sign industry, a plurality of. neon units are frequently connected in series to a common power source, usually a transformer. Each neon unit is defined as a single length of neon tube having' electrodes in the opposite ends thereof, and this single neon tube is normally shaped to form only a portion of a complete 'Neon sign. When, the tube of a neon unit is broken, or when the unit becomes faulty for any reason, the entire circuit in which the unit is interposed in broken, and the entire sign will be turned off.

Several different designs of devices for shunting the current around a neon unit have been proposed, but none ofthese prior devices have been widely accepted in the industry. These prior'shuntingdevices have operated on the principle of a fuse wherein arcing is created between a fuse member and a contact when a neon unitis broken to sever the fuse member and allow engagement of a pair of contacts. The fuse member is'ordinarily used in the nature of tension spring to retain a. movable contact in spaced relation from'a stationary contact, which requires a complicated and expensive manufacturing operation.

The present invention contemplates a novel shunting device which may-be easilyand conveniently connected across any type of neon unit and willquickly short-circuit the neon unit in the event the neon unit becomes faulty. The present invention contemplates the use of a springloaded conductor held in arcing relation with respect to a contactby athermo-plasticrs pacer in such a manner that the; spring-loaded conductor becomes heated upon arcing between the conductor and contacts to, in efiect, melt the therrnd-pl'asticfspacer and allow direct engagement of, the spring-loaded conductor with the contact. 'The springloaded conductor, associated contacts and spacer may be easilyinounted-ina closed tube to prevent the entrance of dirt or othe'r'foreign matter in the space between the springfloaded conductor and the contact, and the entire device may be assembled in the most economical and convenient manner.

'Infits' broader aspects, the present inventionmay be defined as a device for shunting a faulty neon unit. or, the likeh "age parrot spaced, electrodes, comprising a noncondt t ng support,'a pairjoflcontactsfmounted in'spaced regs, on on theeupport, afirst lead,se ured to one ofsaid contacts ferconnectionwith onebrrhe ne'on'unitelectrodes, a s econdlead secured; to the other ofv said con ffoj C(ififl'ebtiodwith the otherneon "unit electrode, a P, grl ad d' l ld c d f aving one, portioiif thereof sec'ur'ed toffoneof'said contacts and 'havi ng" another portion tsereerjbiasednewa d the other ofj said contacts, and a non conducting thermo-pla sticspa cer carried by said sup port and engaging: said conductor forretaining said other portion of saidconductor an arcing distance from, said other contact, said spacer being responsive to. heating of. said conductor resulting front-arcing 'between said conductor and .saidother contact to release said conductor forimove'ment' into engagement withsaid other contact. f

An important object of this invention is to provide an efficient 'shunting d evicefor'faulty neon units and the like atnt which may be easily connected across any sizeor type of neon unit and which will efficiently shunt the neon unit when the neon unit is broken or otherwise becomes non-conducting.

Another object of this invention is to provide a device for shunting a faulty neon unit or the like which may be easily designed for any desired power requirements.

A further object of this invention is to provide a shunting device which may be installed in an exposed position and will not be rendered inoperative by the action of weather.

Another object of this invention is to protect a complete Neon sign against interruption of current through the sign for an extended period of time.

Another object of this invention is to provide a shunting device utilizing the simplest fastening devices and which requires no fuse element held under tension.

A still further object of this invention is to provide a shunting device which is simply constructed, may be economically manufactured and which will have a long service life.

Other objects and advantages of the invention will be evident from the following detailed description, when read in conjunction with the accompanying drawings which illustrate my invention.

In the drawings:

FIGURE '1 is a schematic wiring diagram illustrating the connections, in a Neon sign, of a plurality of shunting devices constructed in accordance with this invention.

FIGURE 2 is a longitudinal sectional view through a shunting device constructed in accordance with this invention.

FIGURE 3 is an enlarged perspective view showing the construction of the thermo-plastic spacer and the position of the spring-loaded conductor in arcing position.

Referring to the drawings in detail, and particularly,

' shunting device'lS is preferably connected across the electrodes 16 of each neon unit 12 of the sign 10.

As shown in FIG. 2', each shunting device 18 comprises a tube 20 of any suitable.non-conductingmaterial, such as glass, and end plates 22 sealed. to the opposite-ends of the tube 20. .In a preferred construction, each end,

platen is in the form of a washer having the central v portion 24 thereof dished inwardly at a diameter corre sponding to the inner diameter of the, tubev 20'to facilitate the insertion of theend plates 22' into the opposite ends,

of thetub'e 20, .as illustrated in the drawing. Also, each end 26 or the tube: 201s preferablybev'eled or tapered away from the respective end plate 22 to form an annular chamber around each end offthe tubeZO; between the tube 20 and'the outer portion of the respective end plate 22, for reception ofa sealing material 2.8., The sealing ma terial 28 may beof anytype which will provide an airtight seal between the'end plates 22 and the ends of the tube 20, andmay be, for example, a product named Acryloid Bj-7, manufactured by Cadillac Manufacturing Co. of Dallas, Texas. It may also be noted that each end plate 22 may be formed out of any suitableinaterial.

which is easil'y shapedinto a dishediconfigurationas illus- Each neon unit 12 is provided 3 as a plate of mica, is positioned in the central portion of the tube 20. It will also be observed that the support member 30 has a length less than the length of the tube 29. A pair of contacts 32 and 34 are mounted in spaced relation on the support member 30 and are suitably secured in conducting relation with a pair of leads 36 and 38. Each of the leads 36 and 38 preferably comprises'a length of stranded wire to facilitate the connection of the leads across the electrodes 16 of the respective neon unit 12 in the manner illustrated in FIG. 1. Each of the leads 36 and 38extends through an aperture 40 formed in the central portion of the respective end plate 22 of the device 18 and is soldered to the respective end plate by solder 42, such that the support member 30 will be secured in a fixed position in the tube 20 and the leads 36 and 38 may be easily connected to the electrodes 16 without possible damage to the elements contained within the tube 20.

A spring-loaded conductor 44 is secured to one of the contacts 32 at one end 46 thereof and extends generally toward the other contact 34. In a preferred construction, the conductor 44 is in the form of a spring wire with the end 48 thereof bent toward, and then transversely with respect to, the contact 34, as most clearly shown in FIG. 3. The conductor 44 is sprung away from the support 30 and held with the end 48 thereof in spaced relation from the contact 34 by a spacer 50 formed of a suitable thermo-plastic material which will either melt or become extremely plastic when heated by the conductor 44, such as Acetate Butyrate, sold by Chicago Molding Co. of Chicago, Illinois. The spacer 50 is preferably in the form of a plate bent to provide flange portions 52 and 54 extending at right angles to one another. The flange portion 52 is positioned in contact with the support member 30, and the flange portion 54 extends outwardly from the support member 30 into engagement with the conductor 44 adjacent the end 48 thereof. Also, as shown in FIG. 3, a V-shaped notch 56 is preferably provided in the outer end of the flange portion 54 to retain the conductor 44 in alignment with the contacts 32 and 34 when the conductor is in the position shown in FIGS. 2 and 3. A slot 58 is provided in one edge of the flange portion 54 extending between the conductor 44 and the support member 30 to facilitate the ease of movement of the conductor 44 when the spacer 50 becomes heated. In other words, the slot 58 controls the strength of the spacer 50 in an economical and efiicient manner.

In a preferred embodiment of this invention, each of the contacts 32 and 34 is in the form of a U-shaped cleat which is placed around the respective portion of the support 30 and then pressed together over the respective lead 36 or 38 to provide an efficient engagement of the contacts with the leads. Also, the end portion 46 of the conductor 44 is placed between the opposite sides of the contact 32 in contact with the lead 36 prior to the pressing of the contact 32, to rigidly secure the'end portion 46 of the conductor 44 to the support member 30. Theopposite contact 34 is extended over the flange portion 52 of the spacer 50, as well as over the lead 38, to rigidly support the spacer 50 in the desired position.

When one of the devices 18 is connected across the electrodes 16 of each of the neon units 12 in the manner illustrated in FIG. 1, the distance between the end 48 of the conductor 44 and the contact 34 will be less than the distance between the electrodes 16 of the respective unit 12. Therefore, when the tube of the respective unit 12 breaks, or when the unit 12 becomes non-conducting for any reason, an arc will occur between the end 48 of the conductor 44 and the contact 34 which heats the conductor 44. Heat dissipated by the conductor 44 will either melt the thermo-plastic spacer 50 or will render the thermo-plastic spacer 50 highly plastic, such that the conductor 44 will spring toward'the support member 30 over or through the flange portion 54 of the spacer and bring the end 48 of the conductor into engagement with the contact 34; whereupon current will flow through the device 18 to short-circuit or shunt the respective neon unit 12. It will be apparent that the size of the spacer 50 and the configuration of the conductor 44 may be designed to position the end48 of the conductor from the contact 34 a distance which will provide an arcing between these two points when the neon unit 12 becomes faulty, without affecting the normal operation of the neon unit 12.

From the foregoing it will be apparent that the present invention provides a novel shunting device which will provide adequate protection for a complete Neon sign and prevent the complete sign from going out in the event one of the units of the sign is broken or the like. The present shunting device is usable on any Neon sign construction and will be unafiected by adverse weather con ditions, as well as be protected against the entrance of dirt or other foreign matter between the working parts of the device. It will also be apparent that only two fasteners are required for the working parts of the device, and these fasteners are preferably in the form of simple U-shaped cleats which also function as contacts to provide the most economical construction. it will be apparent that the present shunting device will have the maximum service life, until it is energized by a faulty neon unit, is simple in construction and may be economically manufactured and used.

Changes may be made in the combination and arrangement of parts or elements as heretofore set forth in the specification and shown in the drawings, it being understood that changes may be made in the precise embodiment disclosed without departing from the spirit and scope of the invention as defined in the following claims.

Iclaim:

1. A device for shunting a faulty neon unit or the like having a pair of spaced electrodes, comprising a nonconducting support, a pair of contacts mounted in spaced relation on the support, a first lead secured to one of said contacts for connection with one of the neon unit electrodes, a second lead secured to the other of said contacts for connection with the other neon unit electrode, a spring-loaded conductor having one portion thereof se-' cured to one of said contacts and having another portion thereof biased toward the other of said contacts, and a non-conducting thermo-plastic spacer connected to said support by said other contact and engaging said conductor for retaining said other portion of said conductor an arcing distance from said other contact, said spacer being responsive to heating of said conductor resulting from arcing between said conductor and said other contact to release said conductor for movement into engagement with said other contact.

2. A device as defined in claim 1 wherein said conductor is in the form of a spring wire having a length slightly greater than the distance between said contacts, one end of said wire being secured to the said one contact and the opposite end portion of said wire being bent toward said other contact when the wire is held by said spacer.

3. A device as defined in claim 2 wherein said support is in the form of an elongated plate, each of said contacts comprises a U-shaped cleat pressed around a portion of said plate and the respective lead, and said cleat forming said one contact also being pressed over said one end of said wire.

4. A device as defined in claim 3 wherein said spacer is in the form of a plate bent to form two flange portions extending at right angles to one another, one of said flange portions being extended through the cleat forming Finally,

its outer end V-shaped to hold such spring wire in alignment with said contacts, and has a slot in one side thereof extending between said spring Wire and said support.

6. A device for shunting a faulty neon unit or the like having a pair of spaced electrodes, the device comprising: a non-conducting elongated support; a first lead, an elongated spring-loaded conductor, and a first contact comprised of a U-shaped cleat, the first lead and one end of the conductor being clamped to one end of the support by the first contact; and, a second lead, a therrno-plastic spacer, and a second contact comprised of a U-shaped cleat, the second lead and the thermoplastic spacer being clamped to the other end of the support by the second contact; the spring-loaded conductor having the other end biased toward the second contact and held in spaced, arcing relation therefrom by the thermo-plastic spacer whereby a high voltage applied to the leads will cause arcing across the space between the spring-loaded conductor and the second contact; the thermo-plastic spacer being responsive to heating of said conductor resulting from the arcing to release the conductor for movement into engagement with the second contact to complete a shunting circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,242,333 Eddy Oct. 9, 1917 1,955,571 Wood Apr. 7, 1934 2,105,113 Gibson Jan. 11, 1938 2,528,096 Ward Oct. 31, 1950 2,530,228 Cihlar et a1 Nov. 14, 1950 

